var linesToSkip = reader.LineNumber - 1;
var charsToSkip = reader.LinePosition;
reader.Close();
if (linesToSkip > 0)
    lines.RemoveRange(0, linesToSkip);
lines[0] = lines[0].Substring(charsToSkip + 1);
text = string.Join("\n", lines);
reader = new JsonTextReader(new StringReader(text));